Excellent Durability of Carbon-Supported Pt Cathode Catalysts Covered with Silica Layers

摘要

Multi-walled carbon nanotube-supported platinum electrocatalysts (Pt/CNT) for cathode in polymer electrolyte fuel cells were covered with silica layers (SiO_2/Pt/CNT) in order to improve the durability. SiO_2/Pt/CNT had a high catalytic activity in spite of uniform coverage of Pt metal with silica which was an insulator. The catalytic activity of SiO_2/Pt/CNT did not change appreciably during the durability test (repeated potential cycling between 0.05 and 1.20V vs. RHE), whereas Pt/CNT was seriously deactivated. Silica layer which enveloped Pt metal particles in SiO_2/Pt/CNT prevented the agglomeration of Pt metal particles as well as the growth of Pt metal particles in size through dissolution and redeposition of Pt metal.